Fatal error: Uncaught Error: Class "Symfony\Component\Form\AbstractExtension" not found in /home/marcgron/www/SSA/v2/vendor/symfony/form/Extension/HttpFoundation/HttpFoundationExtension.php:21 Stack trace: #0 {main} thrown in /home/marcgron/www/SSA/v2/vendor/symfony/form/Extension/HttpFoundation/HttpFoundationExtension.php on line 21